I'm not opposed to having the Best in Show award again for Cosplay Skit competition, the only downside I continuously saw year after year is that it did not give the opportunity for those in a lower performance class to win, in fact they would rarely, sometimes never win anything. Thus be the only reason why the Grand Prize for each division is present.

Can you not have Best in Class + a Best in Show award? In my experience with other contests with class systems you compete against your division for the best in class titles but everyone is eligible for best in show. I have also seen lower classes pull the BIS title so it is not always biased to the highest class.

You can take a look at San Japan and Anime Matsuri's rules if you want some concrete examples, both of them have been running a class system for many years.